Motion controlled systems are equipped with motion sensing input devices that allow a human user to control a virtual object, such as a cursor or character, in a virtual environment or interface through natural movement of the human user. One example motion controlled system is the KINECT® by MICROSOFT®. In a KINECT® system, motion input is captured in three-dimensional space using sensors that detect infrared radiation and sensors that detect visible light. The motion input is transformed into a three-dimensional skeleton of the human user, and the skeleton is periodically updated as the human user moves in a physical environment. Movement of the skeleton may control a cursor or character on the screen such that the cursor or character moves in a manner that roughly corresponds with the movement of the human user in the physical environment.
Unlike mouse input, motion input includes positions of joints or tracked body parts of a human user, optionally in three-dimensional space. These tracked body parts may be in any configuration, moving in any direction, and it is difficult to predict how human users will interact with motion controlled systems.
Due to the complexities of motion input, such input is often mapped directly to the virtual objects that are being controlled by the motion input. For example, a position of a user's hand may be mapped directly to a position of a cursor on the screen. As another example, a configuration of a user's arms and legs may be mapped directly to a configuration of a character's arms and legs on the screen. As a result, functionality of motion controlled systems is quite limited, and simple games such as FRUIT NINJA® or KINECT® Sports have been the most successful applications of these motion controlled systems. In FRUIT NINJA®, for example, the hands of the human user are mapped to hands or blades for slicing fruit in a virtual environment.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.